Air conditioning apparatus



G. A. +1 LLEY 2,420,93

am comanmwwe Tus Film Nov. 11. 1%

Denied Air ZSnoentor GILBERT A. Kan.

' (Itfomeg Patented May 20, 1947 2,420,993 AIR CONDITIONING APPARATUSGilbert A. Kelley, Toledo, Ohio, assignor to Surface CombustionCorporation, Toledo, Ohio, a corporation of Ohio Application November11, 1943, Serial No. 509,928

1 Claim. (Cl. 236-44) l 2 This invention relates to apparatus fordehucase when the wet bulb is located in the relatively midifying air bymeans of a hygroscopic liquid dry treated air. Also, d o he change insuch as a solution of lithium chloride or other hytion. a false readingof the wet bulb thermostat,

groscopic salt. The moisture absorbing capacity as will be shown later,does not critically affect of a hygroscopic liquid varies inversely withthe 5 the control of the leaving air as is the case when temperature ofthe liquid, and it has been prothe wet bulb thermostat is in the leavingair. posed to control the moisture content of the In accordance with thepresent invention a treated air by controlling the temperature of thethermostat responsive to the temperature of the said liquid by meansincluding a dry bulb and a hygroscopic solution flowing to the air andliquid wet bulb thermostat located in the stream of contact means isprovided for maintaining the treated air from the apparatus. saidtemperature substantially constant and the Any deposit on the wet bulbinstrument, such wet bulb thermostat is employed for adjusting the assalt accumulation due to rapid evaporation of setting of the solutionthermostat to maintain a water at low vapor pressures or dirt collectingon higher or lower solution temperature depending the wet bulb willresult in a high wet bulb read on whether the wet bulb temperature ofthe ening. For example, if the job is designed to maintering airdecreases or increases, respectively. tain 95 dry bulb, 64 wet bulb, and40 grains of The particular solution temperature required to moistureper pound of dry air from the dehumidiproduce a particular moisturecontent in the air fying equipment, a rise of 1 in wet bulb readingdepends on the particular hygroscopic solution due to fouling of the wetbulb will cause the conemployed and on the concentration of the solutrolto maintain 63 wet bulb when 64 wet bulb tion. The following scheduleshows what the is indicated by wet bulb instrument. This falsetemperatures of a lithium chloride solution of a reading will thenmaintain 95 dry bulb, 63 wet certain concentration should be to maintaina bulb, 35 grains of moisture per pound of dry air, certain moisturecontent in the treated air under although the control indicates 40grains of mols a y g Wet bulb temperatures of the untreated ture perpound oi. dry air. air.

This variation is satisfactory in some installations but is not goodenough for control for im- Lithium portant industrial processingapplication such as Wet Chloride dry blast air to a blast furnace orcupola or on Bulb s f igg other industrial processing jobs where it isnecesp sary to maintain the moisture content of the air Dem Dem duringan entire year's operation within. say, plus so 94.3 or minus 2 grainsof moisture per pound of dry air. 5 The object of the present inventionis to pro- 55 6118 vide a control system which shall embody a wet 88-;bulb thermostat but which shall nevertheless permit a closer control ofthe moisture content of the treated air to be maintained than hashereto- For any given chemical dehumidifying solution fore been possiblewith control systems embody- 40 the wet bulb temperature of the air tothe equiping a wet bulb thermostat in the treated air for ment isrepresentative of the total amount of controlling the temperature of thehygroscopic work to be done on the air for a given temperature liquid.and concentration of the solution. The above In accordance with thepresent invention the schedule will maintain the moisture content of wetbulb thermostat is not located in the stream the treated air during anentire season's operaof treated air from the dehumidifying apparatustion within the limits of from 34 to 38 grains of but in the stream ofuntreated air flowing to the moisture per pound of dry air in theleaving air apparatus for contact with the hygroscopic liquid. whennothing more than a wet bulb thermostat This change of location of thewet bulb thermois used to reset the liquid temperature controller. statis an important feature of the invention, be- If a more accurate controlthan this is desired, cause for one thing due to the relatively higheran instrument or combination of instruments remoisture content of theuntreated air and, theresponsive to the moisture content of theuntreated fore, higher vapor pressure of the wick water air can beplaced in the untreated air. One fouling of the wet bulb by saltdeposits from the method of accomplishing this would be to place wickwater is a much slower process than is the a dry bulb and a wet bulbthermostat in the un- 3 treated air with means to keep the air to thedry bulb thermostat at constant dry bulb temperature. The variation inthe wet bulb temperature will then be representative of the moisturecontent of the air and will adjust the settingot the solution thermostatto maintain a higher or lower solution temperature depending on whetherthe moisture content or the entering air decreases or increases,respectively.

By placing the wet bulb thermostat in the entering air, there is lesslikelihood salt deposits or other contamination on the wick causingin... adequate control due to faulty wet bulb readings. For example, awet bulb controller in the leaving air from the equipment and whichreads 3 higher than the correct wet bulb temperature would, when theequipment is designed for 95 dry bulb. 64 wet bulb, give an error of 15grains of moisture per pound of dry. air in the leaving air. Thisdifference would cause trouble in many industrial processes. However, ifthe wet bulb controller is in the entering air and is operatingaccording to the schedule outlined above an error of 3 in the wet bulbcontroller would only result in a change in the leaving air ofapproximately 1 grain of moisture per pound of dry air.

In the accompanying drawing forming part of this specification, thesingle view is a more or.

less diagrammatic representation of a chemical dehumidifying systemembodying the present invention.

In the drawing l0 indicates a sump or container for a body ofhygroscopic liquid which for the purpose of this description can beconsidered as being a solution of lithium chloride. Liquid from the sumpand the air to be treated are brought together in intimate contact in agas and liquid contact means schematically indicated at H inside 01' ahousing or casing [2 to which the air to be treated is delivered by aconduit l3 and from which the treated air flows by way of a conduit 84in which is a suction fan l5 for causing the air from conduit Hi to flowupward through the contactor H. The spent solution flows back to thesump H! by way of a return pipe [6 from the bottom of the casing I2. Anypreierred means generally indicated at H is employed for maintaining theliquid in the sump at a substantially constant concentration. Liquidfrom the sump I0 is delivered to the contactor II by means comprising apump 18 in a supply line 19 which delivers to a spray head 20 above thecontactor. The construction thus far described represents nothing new.

In the supply line l9 leading from the sump III to the spray head 20, athermostat 2| is immersed in the solution flowing to the spray head forso controlling the operation of a heat exchanger 22 that the solutionsupplied to said spray head will be at a substantially constanttemperature depending on the setting of the thermostat. For the purposeof this description the heat exchanger can be considered a heaterembodying a steam coil to which the flow of steam is controlled by avalve 23 whose setting is controlled by the thermostat 2| as indicatedby the connection 24. To insure that the solution flowing to the heater22 is relatively cool, there is shown as interposed in the supply lineling the flow of cooling fluid such as cold water to the cooler.

In accordance with the present invention the temperature of thehygroscopic solution supplied to the spray head 20 is increased ordecreased a predetermined degree depending on the decrease or increaserespectively of the moisture content of the raw or fresh air that isbeing delivered to the dehumidiiying apparatus for treatment. Inaccordance with the present invention this change in temperature of thedehumidii'ying solution is accomplished by adjusting the temperaturesetting of the solution thermostat 2| by means comprising a wet bulbthermostat 28 or its equivalent in. the raw air supply conduit It, theoperating connection between the two thermostats being indicated at 29.The advantages resulting from controlling the temperature of thesolution by means under the control of the moisture content of the rawor untreated air have already been explained. I

The means I! for maintaining the liquid in the sump in at substantiallyconstant concentration has been shown as comprising a casing 30 whereinis housed a steam coil 3| to which the flow of steam is controlled by avalve 32 whose setting is controlled by an instrument 33 responsive tothe density of the liquid in the sump. Disposed over the steam coil is aspray head 34 to which liquid from the sump is conducted by a pipe 35which includes a pump 36. A pipe 31 returns the concentrated liquid backto the sump. Air entering the casing at 38 is drawn through the casingby a suction fan 39 for carrying of! the steam from the heated liquid.

What I claim is:

In-apparatus for treating air to produce a stream of air ofsubstantially constant water vapor content, the combination whichcomprises a dehydrating chamber to which initially separate streams ofair and hygroscopic liquid are conducted for intimate contact with eachother, means comprising an adjustable control means which is responsiveto the temperature of the hygroscopic liquid being conducted to saidchamber for maintaining the said temperature substantially constantdepending on the setting of said control means. and means comprising awet bulb thermostat responsive to the wet bulb temperature of the fullcomplement of the air bein conducted to said dehydrating chamber foradlusting the setting of the said control means in such direction as toinsure an increase or decrease in the temperature of the said liquid inaccordance as the said wet bulb temperature decreases or increases,respectively.

GILBERT A. KELLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,019,291 Brace et al. Oct. 29,1935 2,133,334 Rosett Oct. 18, 1938

